Google today promoted the 64-bit Windows version of Chrome to a pair of preview channels, and promised that the browser is more stable and faster than its 32-bit sibling.

The new 64-bit Chrome was advanced to the "Canary" and "Dev" channels, the two least-polished builds in the four channels Google maintains.

"The new version replaces the existing version while preserving all your settings and bookmarks, so there's no need to uninstall a current installation of Chrome," wrote Will Harris, a Chrome software engineer, in an entry on the Chromium blog.

Chromium is the name for the open-source project that feeds code into Chrome.

Harris touted the 64-bit browser as 25% faster in rendering graphics and multimedia content, and boasted it showed "a marked increase in stability ... over 32-bit Chrome" with half the crashes.

The Windows 64-bit Chrome will run on Windows 7 and Windows 8, said Harris.

Apple's Safari has been 64-bit on OS X -- its only supported platform at this point -- since 2009's version 4, which launched alongside OS X Snow Leopard. Microsoft's Internet Explorer has been available in 64-bit since Windows 2006's IE7, while Opera Software, the Norwegian browser maker known for its same-named desktop flagship, also offers a 64-bit edition on Windows.

But Google and Mozilla have been slower to adopt 64-bit. Google currently offers a 64-bit browser for Linux, and is working on one for OS X. The latter is only available in Chromium, the pre-Canary build, and has been marked as experimental. It requires OS X Mountain Lion or later.

Mozilla has long had 64-bit versions of Firefox for OS X and Linux, but has yet to push a 64-bit Windows edition into its prime release channels. However, one is available on Mozilla's "Nightly" build line, which is analogous to Chrome's Canary.

"For 64-bit Firefox on Windows, we are in the process of setting up our automated testing for this platform to make sure that it gets the same daily testing coverage as all of our other platforms do," said Firefox engineering director Vladimir Vukicevic, in an email reply to questions Tuesday. "Once we have continuous testing set up, we should have more news to share about timing for a full 64-bit Firefox release on Windows."

That Nightly build of 64-bit Firefox on Windows can be downloaded from Mozilla's website ( download installer).

Mozilla's work on Firefox 64-bit for Windows wasn't helped by a work stoppage in November 2012, when the company cited add-on incompatibilities -- a long-standing bugaboo for every 64-bit browser -- and a low priority for halting development.